Strong and lightweight building materials that are both easily and economically manufactured have long been sought by those working in the building and construction trades. Because of their excellent resistance to heat transfer, fire, weathering, and the like, in addition to their strength and low density, mineral foams have proven to be particularly desirable and useful in building applications. These foamed compositions are referred to generally in the art as foamed ceramics, foamed refractories or mineral foams and are characterized by their ability to set or harden into a rigid mass once they have been expanded by gas bubbles that are generated either internally or externally with or without the addition of heat. Such compositions are disclosed, for example, in U.S. Pat. Nos. 3,136,645 to Dess; 3,148,996 to Vukasovich, et al; 3,150,988 to Dess et al; and 3,625,723 to Sicka.
Nevertheless, such references have required the use of acidic phosphates, fluosilicates, organic surfactants, emulsifiers, and the like to achieve the fluidity and foaming characteristics. In most applications, mineral foam compositions are pumped or poured into forms, or sprayed onto a supporting surface, and are thereafter either permitted or caused through the addition of heat to expand and solidify. Satisfactory mineral foam compositions for use in the building and construction industry should be fluid enough to facilitate emplacement and expansion, yet thick enough to resist over-expansion and to form a strong and insulative mass when set. An improved foam composition is needed that achieves these desirable results without the use of phosphates, fluosilicates, organic surfactants, or emulsifiers.
Furthermore, while the use of acid treated silicon as a foaming agent has been previously disclosed, a process is needed for employing silicon in mineral foam compositions without requiring prior acid treatment to remove any oxides that may be present.
Because it is expected that mineral foam compositions will be made and used over a wide range of ambient temperatures, depending upon the location, climate, season, etc., attendant at any particular construction site, compositions and processes are also needed that are not appreciably affected by temperature variations that might normally be encountered.